The present invention relates to a bore cutter.
Conventional bore cutters of the type described below are known. That is, a number of bore blade portions are provided on the outer periphery of a rotary shaft at equal angular intervals in the circumference with the rotation axis as the center. All of these blade portions have a discontinuous blade having a blade edge in uneven form. These continuous blades have a number of protruding blade edges and indented blade edges which are alternately provided along the rotation axis. The distance of these protruding blade edges from the rotation axis (distance in the radial direction) is set so as to be the same. The distance of these indented blade edges from the rotation axis is also set so as to be the same. The size of these protruding blade edges in the longitudinal direction is set so as to be equal to the size of the indented blades in the longitudinal direction. Furthermore, the depth of all the indented blades is set so as to be equal.
In each pair of circumferentially adjacent blade portion, the protruding edge and the indented edge of the discontinuous blade in one of the blade portions and those of the other blade portion are displaced from each other along the above described rotation axis. When the bore cutter is used, first, a workpiece, or an object in which a hole is to be bored, is cut by the discontinuous blade in one of a circumferentially adjacent pair of blade portions in such a manner that the internal peripheral surface of the object becomes of an uneven form. Next, the workpiece is cut by the discontinuous blade in the other blade portion, and thereby, the protruding portions are cut off.
In such conventional bore cutters, however, discontinuous blades, of which the number of steps for processing is great, are provided in all of the bore blade portions. Accordingly, processing of bore cutters becomes troublesome, and the manufacturing cost increases.